Microdispensing pump

Abstract

A pre-compression pump ( 10 ) dispenses microdoses of fluid (F). The pump minimizes pulsing due to pressure fluctuations. The pump is provided with the following to limit pulsing: a low force slow return velocity return spring ( 46 ); enlarged fluid passage ( 58 ); elastic bumper ( 74 ); and, a rachet tooth ( 76 ) bearing against the stem ( 44 ). Further, a deflectable diaphragm ( 90 ), a splined ( 70 ) stem ( 44 ), no dip tube, and an off-center, gravitational low-point pump inlet ( 62 ) assist in printing the pump. The pump includes a stem ( 44 ) with deflectable fingers ( 92 ) to ensure sufficient momentum in pump operation. Detents ( 118 ) and grooves ( 120 ) selectively lock a nozzle cap ( 14 ) in an inoperative position. To ensure cleanliness, nozzle ( 60 ) cleaning is provided, wiping of the nozzle to remove meniscus (M) therefrom, cuts ( 104 ) formed in a shroud ( 98 ) assist in drawing excess fluid from the nozzle, and an empty volume ( 108 ) for collecting fluid run-off from the nozzle. A handle (H) is mounted to the pump providing a grip.

1 . A pump for dispensing fluid, said pump comprising: 
 a pump body having a pump cylinder and a fluid reservoir for accommodating the fluid, an inlet being formed in said pump cylinder in communication with said pump reservoir; and a nozzle.    
   
   
       2 . A pump as in  claim 1 , wherein said pump cylinder is disposed within, and extends substantially coextensively with, said fluid reservoir.  
   
   
       3 . A pump as in  claim 2 , wherein said inlet is located in proximity to a wall of said fluid reservoir.  
   
   
       4 . A pump as in  claim 1 , wherein said inlet solely defines a passage for said fluid between said fluid reservoir and said pump cylinder.  
   
   
       5 . A pump as in  claim 4 , wherein said inlet is coextensive with said pump cylinder.  
   
   
       6 . A pump as in  claim 4 , wherein said inlet protrudes slightly from said pump cylinder.  
   
   
       7 . A pump as in  claim 1 , wherein said pump cylinder has a tubular body with a cylindrical wall, a generally open first end, and a generally closed second end, said inlet being formed in said second end, and wherein said second end having an inner surface facing said first end, said inner surface being obliquely disposed relative to said cylindrical wall.  
   
   
       8 . A pump as in  claim 7 , said inlet being formed off-center in said second end so as to be located further from said nozzle than the center of said second end.  
   
   
       9 . A pump as in  claim 8 , wherein said inlet is located gravitationally below said center point.  
   
   
       10 . A pump as in  claim 1 , wherein said pump cylinder has a tubular body with a cylindrical wall, a generally open first end, and a generally closed second end, said inlet being formed in said second end, and wherein said inlet being formed off-center in said second end so as to be located closer to certain portions of said cylindrical wall than other portions of said cylindrical wall.  
   
   
       11 .- 17 . (canceled)  
   
   
       18 . A pump for dispensing fluid, said pump comprising: 
 a pump body; an elongated stem slidably disposed in said pump body; and, a seal immovably mounted relative to said stem, wherein said stem being slidably, and at least partially sealably, disposed in said seal; wherein, said stem is formed with spaced-apart longitudinally extending splines with recesses being defined between said splines, said splines defining an outer diameter which sealingly engages said seal.    
   
   
       19 . A pump as in  claim 18 , wherein said recesses are relatively shallow.  
   
   
       20 . A pump as in  claim 18 , wherein said stem has a constant-diameter portion extending from said splines.  
   
   
       21 . A pump as in  claim 18 , wherein said stem has a conical portion extending from said splines.  
   
   
       22 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a piston slidably disposed with said pump body; a stem slidably disposed within said piston; and, a return spring disposed to urge said stem towards said piston, wherein said stem separates from said piston in dispensing the fluid.    
   
   
       23 . A pump as in  claim 22 , wherein said return spring is formed with a relatively weak spring force so that said stem is separated relatively easily from said piston.  
   
   
       24 . A pump as in  claim 22 , wherein said return spring is wound to have a reduced return velocity.  
   
   
       25 . A pump comprising: 
 a nozzle; a pre-compression pump means for pumping fluid; and, a passage communicating said pump means and said nozzle, said passage having cross-sectionally enlarged portions.    
   
   
       26 . A pump as in  claim 25 , wherein said passage has at least one bend, said bend being cross-sectionally enlarged compared to portions of said passage adjacent to said bend.  
   
   
       27 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle; a stem slidably disposed in said pump body, said stem slidable in directions generally to and away from said nozzle; and, a bumper disposed between said stem and said nozzle.    
   
   
       28 . A pump as in  claim 27 , wherein said bumper is mounted to said stem.  
   
   
       29 . A pump as in  claim 28 , wherein said bumper is an elastically-deformable dome-shaped member mounted onto an end of said stem.  
   
   
       30 . A pump as in  claim 28 , wherein said bumper is an elastically-deformable member at least partially extending from an end of said stem.  
   
   
       31 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a piston slidably disposed in said pump body; a stem slidably disposed in said piston; and, at least one ratchet tooth disposed on said piston, said ratchet tooth bearing against said stem.    
   
   
       32 . A pump as in  claim 31 , wherein said ratchet tooth is generally plate-shaped.  
   
   
       33 . A pump as in  claim 31 , wherein said ratchet tooth has a generally triangular profile with an edge of said ratchet tooth bearing against said stem.  
   
   
       34 . A pump as in  claim 31 , wherein said ratchet tooth bears against said stem continuously.  
   
   
       35 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle cap operatively mounted to said pump body, a nozzle being disposed in said nozzle cap; and, a shroud rigidly fixed to said pump body, said shroud having an opening formed therethrough for registering with said nozzle during activation so as to allow an amount of dispensed fluid to pass through said shroud from said nozzle, wherein said nozzle moves relative to said shroud during operation, and wherein a portion of said shroud being disposed in proximity to said nozzle such that any meniscus of the fluid formed on said nozzle after dispensing is at least partially wiped by said opening with said nozzle moving relative thereto.    
   
   
       36 . A pump as in  claim 35 , wherein portions of said shroud disposed about said opening and facing said nozzle cap are roughened.  
   
   
       37 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle cap operatively mounted to said pump body, a nozzle being disposed in said nozzle cap; and, a shroud rigidly fixed to said pump body, said shroud having an opening formed therethrough for registering with said nozzle during operation so as to allow an amount of dispensed fluid to pass through said shroud from said nozzle, wherein a plurality of cuts are formed in said shroud about said opening, said cuts being spaced-apart so that a plurality of lands are formed about said opening.    
   
   
       38 . A pump as in  claim 37 , wherein said cuts radiate from said opening.  
   
   
       39 . A pump as in  claim 38 , wherein said cuts taper apart in radiating from said opening.  
   
   
       40 . A pump as in  claim 37 , wherein said lands are roughened.  
   
   
       41 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle cap operatively mounted to said pump body, a nozzle being disposed in said nozzle cap; and, a shroud rigidly fixed to said pump body, said shroud having an opening formed therethrough for registering with said nozzle during operation so as to allow an amount of dispensed fluid to pass through said shroud from said nozzle, said shroud partially encompassing an empty void defined externally of said nozzle cap and about said nozzle.    
   
   
       42 . A pump as in  claim 41 , wherein said nozzle protrudes from said nozzle cap so as to define a free end spaced from said nozzle cap.  
   
   
       43 . A pump as in  claim 42 , wherein said free end of said nozzle is rounded.  
   
   
       44 . A pump as in  claim 43 , wherein said free end is rounded with a radius of 0.005 inches.  
   
   
       45 . A pump as in  claim 42 , wherein said free end is roughened.  
   
   
       46 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle cap operatively mounted to said pump body, a nozzle being disposed in said nozzle cap; and, a shroud rigidly fixed to said pump body, said shroud having an opening formed therethrough for registering with said nozzle during operation so as to allow an amount of dispensed fluid to pass through said shroud from said nozzle, wherein said nozzle cap is rotatable relative to said shroud, at least one detent being formed on one of said shroud and said nozzle cap, at least one groove being formed to receive in seating engagement said detent, and wherein said groove is positioned to receive said detent in seating engagement with said nozzle being rotated away from said opening into a locked position.    
   
   
       47 . A pump as in  claim 46 , wherein at least two pairs of detents and grooves are provided.  
   
   
       48 . A pump as in  claim 46 , wherein said nozzle cap is formed with a solid portion in registration with each of said detents in said locked position, the registration of said detents and said solid portions preventing activation of said nozzle cap.  
   
   
       49 . A pump for dispensing fluid, said pump comprising: 
 a pump body having a wholly contained fluid reservoir; and, a tubular handle extending from said pump body.    
   
   
       50 . A pump as in  claim 49 , wherein said handle has a closed end.  
   
   
       51 . (canceled)  
   
   
       52 . A pump for dispensing fluid, said pump comprising: 
 a pump body; a nozzle cap operatively mounted to said pump body, a nozzle being disposed in said nozzle cap; and a shroud rigidly fixed to said pump body, said shroud having an opening formed therethrough for registering with said nozzle during operation so as to allow an amount of dispensed fluid to pass through said shroud from said nozzle, wherein said nozzle cap is rotatable relative. to said shroud, wherein said nozzle cap being formed with at least one radially extending sealing member, said shroud being formed with at least one inwardly extending shroud sealing member, said sealing members being located to overlap with said nozzle cap being rotated to a pre-determined position relative to said shroud.    
   
   
       53 . (canceled)